1. Field of the Invention
The present invention relates to a method and device for collecting particulate contaminants removed using a CO2 decontamination medium from an early stage of a decontamination process. More particularly, the present invention relates to a device for collecting particulate contaminants during a CO2 blasting decontamination process, which is readily combined with a conventional CO2 blasting nozzle unit to collect particulate contaminants, allowing compressed gas blasted through an air curtain blasting nozzle of the device to prevent contaminated gas from diffusing into the atmosphere, and sucking particulate contaminants into a separate collecting filter, and a method of collecting particulate contaminants using the device.
2. Description of the Prior Art
As well known to those skilled in the art, recently, CO2 decontamination processes have attracted considerable attention even though these various decontamination processes are applied to industrial fields. In comparison with conventional chemical and physical decontamination processes, the CO2 decontamination process has advantages of cleanness, rapid decontamination speed, and not producing secondary wastes, thus it is frequently applied to various fields such as atomic piles, semiconductor fabrication, and optical and medical equipment.
If CO2 gas at a very low temperature passes through an orifice of a nozzle under conditions in which liquid phase and vapor phase coexist (pressure of 800 psi) to be dropped to 80 psi in pressure, a portion of high-pressure CO2 gas (about 45%) is converted into solid granules like snow. These granules consist of crystal particles of sub-micron units, and are blasted onto a subject which is to be decontaminated. This is a CO2 snow-blasting decontamination process.
Additionally, there is a conventional CO2 pellet-blasting decontamination process, in which solid previously-prepared granules are compressed to form predetermined lump-like shapes, and these lumps, or so-called pellets, are blasted onto a contaminated subject to decontaminate the subject.
According to these conventional decontamination processes, a CO2 decontamination medium (CO2 snow or CO2 pellets), when blasting through a nozzle to a surface of a contaminated subject, transfers its collision energy into particulate contaminants to remove them. However, these processes are disadvantageous in that a separate collecting process is additionally needed, thus inevitably increasing decontamination cost.
Other disadvantages of the above processes are that particulate contaminants removed by the CO2 decontamination medium are instantaneously diffused into the atmosphere by the blasting gas, and a freezing layer is formed on a surface of the contaminated subject because a temperature of the blasted CO2 gas is very low, thus reducing decontamination efficiency of the contaminated subject.